The government contract that led interrogators working for CACI International Inc. into Abu Ghraib prison in Iraq was awarded in 1998, with the stated purpose of providing inventory control and other routine services to the U.S. Army.

This kind of "blanket-purchase agreement" is becoming increasingly popular with federal agencies because it is supposed to increase efficiency. Large, vaguely worded contracts are designed so the agencies can make quick requests and get fast results, without requiring separate bids and evaluations for each service. Critics say these open-ended contracts allow agencies to skirt public oversight and give big companies an unfair advantage in winning government business.

The CACI contract with the Army is administered by the Interior Department, under an outsourcing agreement with the Army, which has made it even harder to track.

The CACI contract has a $500 million limit, said Frank Quimby, a spokesman for the Interior Department. CACI has received 80 requests, or delivery orders, from the Army under this contract. Most requests are for CACI's meat-and-potatoes offerings, such as information technology services, but 11 of the delivery orders were for projects in Iraq. Three of those dealt with interrogation and intelligence gathering.

One order, issued in August 2003, was worth $19.9 million for a year-long stint of interrogation support, Quimby said. It is under that order that CACI's Steven A. Stefanowicz and other contractors worked as interrogators at the Abu Ghraib prison near Baghdad. An Army report on abuses at the prison accuses Stefanowicz of encouraging soldiers to "set conditions" for interrogations. The company has not identified Stefanowicz as the employee in question and declined to comment on the details of its contract with the Army.

"If they want to provide information to the media, that's the business of the United States government, that's not the business of CACI," J.P. London, CACI's chairman and chief executive, said in an interview last week. Stefanowicz's lawyer has said that his client did nothing wrong at the prison.

The interrogator request specified that CACI's subsidiary, CACI Premier Technology Inc., provide "intelligence advisors and data base entry-intelligence research clerks." These positions, the delivery order said, "require specific intelligence and technical expertise."

That same month the Army said it would pay CACI $3.2 million to help screen Iraqis for access to U.S. military bases. That year-long project includes "gathering and recording intelligence information electronically, and providing analysts with computer generated intelligence information."

In December 2003, CACI landed a $21.8 million request to help the Army complete "counter intelligence missions at secure and fixed locations." Quimby said all three of the delivery orders were requested by Combined Joint Task Force-7, which is responsible for securing Iraq.

Because CACI had a lock on all of these contracts, none of the requests were announced to the public.

"It's considered this fabulously successful streamlining of the system, but in the process you lose any accountability," said Danielle Brian, executive director of the Project on Government Oversight. Brian said she described large, open contracts like the one given to CACI as "hunting licenses."

"You've been given a license to do business with the government," Brian said. "You've been allowed into the preserve and once you get in there's no competition necessary."

Small companies looking to bid on specific projects may be cut out of the loop because of these types of contracts, Brian added. The agreement with CACI was already in place, so the Army did not have to put out a request for bids from other contractors that may have wanted to compete for the contract.

And because there is no competition to drive down prices, the government may be paying more than it should for some products and services, according to a report on the Defense Department's management challenges released in January by the General Accounting Office.

Throughout the 1990s, many government agencies tried to change the way they did business with private contractors. Removing some of the red tape would make it cheaper for the government and easier for private industry, proponents said.

But training on acquisition procedures and competition requirements within the Defense Department has not kept up with the military's purchasing reforms. As a result, the Defense Department "missed out on opportunities to generate savings, reduce administrative burdens, and enhance outcomes for its acquisitions," the GAO report found.

Blanket-purchase agreements were originally intended for use by agencies that buy routine products and services from the same companies, said Angela Styles, former administrator for federal procurement policy at the Office of Management and Budget. If an agency knows it is going to buy a lot of pencils, for example, it might give a blanket-purchase agreement to Office Depot to lock in a price and expedite billing, she said.

"It's nice to have for simple things. . . . but it's really easy to get out of hand, because the blanket-purchase agreement isn't competed and the work under it isn't competed," Styles said.

Much of the work being done by contractors in Iraq has been parceled out under these large purchasing agreements and "indefinite delivery-indefinite quantity" contracts, said Steve Schooner, co-director of the Government Procurement Law Program at George Washington University. The Iraq reconstruction contracts awarded to Halliburton Co.'s subsidiary, KBR, fall under a similar type of umbrella contract.

When military buyers are "in a hurry or understaffed or when they just feel like it, agencies go out and use these vehicles. And contractors will do whatever you ask them to do, that's their job," Schooner said.

This may help the Defense Department react quickly to changing needs in its wartime and anti-terrorism efforts, Schooner said, but it leaves government watchdogs with much less insight into how tax dollars are being spent.

"There is no question that these flexible vehicles are less transparent than conventional government procurements," Schooner said.